Definition
Remaining Body Wall — Remaining body wall is the percentage of the original nominal wall thickness still present in a used drill pipe tube after wear and corrosion, and it is the primary measurement used to classify pipe as Premium or Class 2.
Also known as: remaining body wall, RBW, remaining wall thickness
What remaining body wall is
Remaining body wall (RBW) expresses how much of a drill pipe tube’s original wall thickness survives after service. It is reported as a percentage of the nominal wall — for example, a joint that has lost a fifth of its wall has 80 percent RBW. Because torsional, tensile, collapse and burst capacities all depend on wall thickness, RBW is the controlling parameter for grading used pipe.
RBW is screened over the full length by electromagnetic inspection (EMI) and then confirmed at the thinnest points by ultrasonic wall gauging. The lowest measured value on a joint governs its class.
How RBW sets the class
- ≥ ~80% RBW — qualifies for Premium Class (subject to other criteria).
- ≥ ~70% RBW — qualifies for Class 2.
- < ~70% RBW — normally rejected.
Because ratings scale with wall, the derated tensile and torsional values published for Premium and Class 2 pipe follow directly from these RBW thresholds.
Why it matters for rentals
RBW is the number that determines the real capacity of a rental joint, so it should be documented in the inspection report. See our drill pipe and quality program, or contact us for wall-thickness records.